At www.answer.com if you type the first letter of a word it gives you suggestions of the rest. I don't think it is javascript. How do they do that? I guess they refresh the frame and get the data from a database everytime we type in something, is that right? .
It is probably AJAX which realistically can only be initialised by javascript. If you do a search on google for AJAX, perhaps with PHP as well then you will learn all about it, it is the same as "google suggest" which i am sure you can read up on as well